U.S. patent application number 10/708603 was filed with the patent office on 2004-10-14 for projecting device with adjustable color temperature.
Invention is credited to Wang, Sze-Ke.
Application Number | 20040201828 10/708603 |
Document ID | / |
Family ID | 32504769 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040201828 |
Kind Code |
A1 |
Wang, Sze-Ke |
October 14, 2004 |
PROJECTING DEVICE WITH ADJUSTABLE COLOR TEMPERATURE
Abstract
An adjustable color-temperature projecting device includes a
light source for providing light beams, and a filtering means. The
filtering means includes red, green and blue filtering sections.
The blue filtering section has coatings with different
transmissivitys. The intensity of blue primary color light is
varied due to the different transmissivitys of the blue filtering
section, so that the ratio of blue primary color light in the
hybrid light is modified to cause change in color temperature with
reduced loss of brightness. Then, the filtering means is moved so
that the light beam is projected onto a predetermined location to
obtain the desired color temperature.
Inventors: |
Wang, Sze-Ke; (Miao-Li
County, TW) |
Correspondence
Address: |
NAIPO (NORTH AMERICA INTERNATIONAL PATENT OFFICE)
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
32504769 |
Appl. No.: |
10/708603 |
Filed: |
March 14, 2004 |
Current U.S.
Class: |
353/84 ;
348/E9.027; 348/E9.051 |
Current CPC
Class: |
H04N 9/3114 20130101;
G02B 27/0927 20130101; G03B 21/20 20130101; H04N 9/73 20130101;
G02B 27/0994 20130101 |
Class at
Publication: |
353/084 |
International
Class: |
G03B 021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2003 |
TW |
092205806 |
Claims
What is claimed is:
1. An adjustable color-temperature projecting device, comprising: a
light source, generating a light beam; and a filtering means,
having at least one red filtering section, a green filtering
section and a blue filtering section, wherein the blue filtering
section has coatings of different transmissivities, and the color
temperature of a hybrid light is changed by moving the filtering
means to modify the location where the light beam passes through
the blue filtering section.
2. The projecting device of claim 1, wherein the coatings with
different transmissivities are arranged in a manner that the
transmissivity gradually changes across the blue filtering
section.
3. The projecting device of claim 1, wherein the blue filtering
section is divided into a plurality of regions on each of which is
applied a coating of different transmissivity.
4. The projecting device of claim 3, wherein the light beam is
projected on a single region.
5. The projecting device of claim 3, wherein the light beam is
projected between two regions.
6. The projecting device of claim 1, wherein the filtering means
further includes a white filtering section.
7. The projecting device of claim 1, wherein the filtering means is
a color wheel.
8. The projecting device of claim 1, wherein an uniformization
element is further mounted at a rear end of the filtering means.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a projecting device, and more
particularly to an adjustable color-temperature projecting
device.
[0003] 2. Description of the Prior Art
[0004] Color temperature brings different visual impressions. For
example, a color of low color temperature gives warm feeling, while
a color of high color temperature gives cool feeling. Therefore,
the color temperature of a projecting device can be adjusted to
satisfy the consumer's demands or visual requirement for different
occasions such as presentation in conferences or movie shows.
[0005] Referring to FIG. 1, a conventional projecting device 10
includes a light source 11, a color wheel 12, an integrated rod 13,
a light valve 14 and a projection lens 15. The color wheel 12
includes red, green and blue color light filters, or alternatively
red, green, blue and white color light filters arranged in circle.
After a light beam emitting from the light source 11 travels
through the color wheel 12, red, green and blue color lights are
subsequently generated and then subjected to uniformization via the
integrated rod 13. Thereafter, the color lights are projected on
the light valve 14. Under control of digital signals from the light
valve 14, the continuous color lights are converted into gray
scales to form an image on a screen 16 via the projection lens 15.
In order to adjust the color temperature, a filtering sheet 17 is
further mounted in front of the projection lens 15. On the
filtering sheet 17 is applied a coating which removes the color
lights of a certain wavelength range. The filtering sheet 17 may be
mutually rotated to attach on or dispatch from the projection lens
15 for change in color temperature. When the filtering sheet 17 is
attached on the projection lens 15, color lights from the
respective filters of the color wheel 12 are processed by the
optical valve 14, then projected on the projection lens 15, and
pass through the filtering sheet 17. The filtering sheet 17 removes
a part of the color light of a certain wavelength range to alter
the spectrum distribution of the red, green and blue color lights,
and thus to cause change in color temperature. Thereby, the image
is displayed on the screen 16. Since all the color lights pass
through the filtering sheet 17 for a further filtering process, a
part of the color lights from the red, green and white filters are
removed, which results in reduced brightness.
SUMMARY OF INVENTION
[0006] One object of the invention is to provide a projecting
device with adjustable color temperature, in which the color
temperature is adjusted by controlling the light beam passing
through a coating with different predetermined transmissivities on
a blue filtering section.
[0007] Another object of the invention is to provide a projecting
device with adjustable color temperature, in which only the
transmittance of the blue filtering section is changeable to reduce
adverse effect on the brightness of the projecting device.
[0008] In order to achieve the above and other objectives, the
projecting device of the invention includes a light source for
providing alight beam, and a filtering means. The filtering means
includes red, green and blue filtering sections. The blue filtering
section has coatings of different transmittances. The intensity of
blue primary color light is varied due to the different
transmissivities of the blue filtering section, so that the ratio
of blue primary color light in a hybrid light is modified to cause
change in color temperature with a reduced loss of brightness.
Then, the filtering means is moved so that the light beam is
projected at a predetermined location to obtain the desired color
temperature.
BRIEF DESCRIPTION OF DRAWINGS
[0009] The drawings included herein provide a further understanding
of the invention. A brief introduction of the drawings is as
follows:
[0010] FIG. 1 is a schematic view of a conventional projecting
device;
[0011] FIG. 2 is a schematic view of a projecting device with
adjustable color temperature according to one embodiment of the
invention;
[0012] FIG. 3 is a front view of a filtering means according to a
first embodiment of the invention;
[0013] FIG. 4 is a graph illustrating the relationship between the
transmissivity and the location of the blue filtering section
according to one embodiment of the invention;
[0014] FIG. 5 is a front view of a filtering means having a white
filtering section according to one embodiment of the invention;
[0015] FIG. 6 is a graph illustrating the relationship between the
wavelength and visual sensitivity; and
[0016] FIG. 7 is a front view of a filtering means according to a
second embodiment of the invention.
DETAILED DESCRIPTION
[0017] To provide a further understanding of the invention, the
following detailed description illustrates embodiments and examples
of the invention, this detailed description being provided only for
illustration of the invention.
[0018] Referring to FIG. 2, a projecting device 20 with adjustable
color temperature according to the invention includes a light
source 21, a filtering means 22, a light valve 23 and a projection
lens 24. The light source 21 generates a light beam which passes
through the filtering means 22 to subsequently generate primary
color lights of red (R), green (G) and blue (B) colors. The primary
color lights then are projected to the light valve 23. Under
control of digital signals of the light valve 23, red, green and
blue color lights are converted into gray scales and then projected
on a screen 25 via the projection lens 24.
[0019] Referring to FIG. 3, the filtering means 22 has at least one
red filtering section 221, one green filtering section 222 and one
blue filtering section 223 to respectively separate red, green and
blue color lights from the light beam. The red filtering section
221 and the green filtering section 222 respectively have constant
transmissivity. The blue filtering section 223 has gradually
changing transmissivities. Referring to FIG. 4, the transmissivity
decreases from the inside to the outside. Furthermore, the
filtering means 22 is a color wheel connected to a moving device
(not shown) to allow linear movement of the filtering means 22. The
filtering means 22 is moved to a predetermined location by means of
the moving device to change the location where the light beam
passes through the blue filtering section 223, thereby changing the
transmissivity and the intensity of blue primary color light
through the blue filtering section 223 to achieve change in color
temperature. For example, when the light beam passes through part A
of the blue filtering section 223 with high transmissivity, a blue
primary light with high intensity is generated. The blue primary
color light is mixed with red and green primary lights that
respectively come from the red and green filtering sections 221,
222 and have constant intensities so as to obtain a hybrid light of
high color temperature, i.e. cool hybrid light. When the light beam
passes through part B of the blue filtering section with low
transmissivity, a blue primary light of low intensity is generated.
The blue primary color light is mixed with the red and green
primary color lights, respectively coming from the red and green
filtering sections 221, 222 and having constant intensities, to
obtain a hybrid light of low color temperature, i.e. warm hybrid
light.
[0020] The transmissivitys vary according to different locations of
the blue filtering section 223. The filtering means 22 is moved by
the moving device to change the location where the light beam is
projected on the filtering means 22 to generate blue primary light
of different intensities. Blue color light of different intensities
is mixed with red and green color lights respectively having
constant transmissivity to achieve adjustment of the color
temperature. Referring to FIG. 5, the filtering means 22 further
has a white filtering section 224 to increase the brightness, while
the transmissivity of other color light filtering sections is kept
constant. When the location where the light beam is projected on
the filtering means 22 is changed, the intensity of the colored
light passing through the white filtering section 224 is not
affected, thereby achieving the adjustment of color temperature
with reduced loss of brightness.
[0021] Furthermore, each part of the red and green filtering
sections 221, 222 has constant transmissivity. Therefore, when the
moving device changes the location where the light beam is
projected on the filtering means 22, only the intensity of blue
primary blue primary light is changeable, while the transmissivity
of other color lights such as green primary light and red primary
light remains unchanged. Therefore, the loss of brightness is
reduced.
[0022] The brightness of color light is the product of irradiancy
with visual sensitivity. FIG. 6 illustrates a relationship between
the wavelength and the visual sensitivity. Referring to FIG. 6,
blue light of wavelength of 380 nm-490 nm has a visual sensitivity
lower than green and red lights. Among the different color lights,
blue light has minimal influence on the brightness. Therefore,
changing the sensitivity of blue primary color light for adjusting
the color temperature is achieved with a reduced loss of
brightness. In other words, the change in color temperature rarely
affects the brightness of an illuminating device.
[0023] Since the transmissivity gradually changes across the blue
filtering section 223, non-uniform color lights therefore are
generated all over the blue filtering section 223. In order to
render the color lights uniform, an uniformization element 26 such
as an integrated rod is further mounted at a rear end of the
filtering means 22 to project a uniform light on the light valve
23.
[0024] Referring to FIG. 7, a filtering means 32 in another
embodiment of the invention includes at least one red filtering
section 321, one green filtering section 322 and one blue filtering
section 323 to separate red, green and blue primary color lights
from the light beam. The red filtering section 321 and the green
filtering section 322 are coatings respectively with constant
transmissivitys. The blue filtering section 323 is divided into a
plurality of regions 3231, 3232 each of which has coatings with
different transmissivities. The region 3231 has a transmissivity
higher than the region 3232. The filtering means 32 is further
connected to a moving device (not shown) to drive the filtering
means 32 to linearly move along the regions 3231, 3232.
[0025] The moving device enables to change the location where the
light beam passes through the blue filtering section 323 to modify
the transmissivity, so that the intensity of blue primary color
light is changed and the color temperature of the hybrid light is
changed. When the light beam passes through the high-transmissivity
region 3231 of the blue filtering section 323, as indicated by C in
FIG. 7, high-intensity blue primary color light is generated. Blue
primary color light then is mixed with red and green primary color
lights, respectively coming from the red and green filtering
sections 321, 322 and having constant intensities, to generate a
hybrid light of high color temperature TH. When the light beam
passes through the low-transmissivity region 3232 of the blue
filtering section 323, as indicated by D in FIG. 7, low-intensity
blue primary color light is generated. The obtained blue light then
is mixed with red and green primary color lights, respectively
coming from the red and green filtering sections 321, 322 and
having constant intensities, to generate a hybrid light of low
color temperature TL. When the light beam passes between the
high-transmissivity region 3231 and the low-transmissivity region
3132, as indicated by E in FIG. 7, a hybrid light of color
temperature ranging form TH to TL is generated according to the
transmission of the light beam between the high-transmissivity
region 3231 and the low-transmissivity region 3132.
[0026] It should be apparent to those skilled in the art that the
above description is only illustrative of specific embodiments and
examples of the invention. The invention should therefore cover
various modifications and variations made to the herein-described
structure and operations of the invention, provided they fall
within the scope of the invention as defined in the following
appended claims.
* * * * *